The present invention relates to suction catheters and, in particular, to nasogastric suction catheters for withdrawing the contents of the stomach of the patient.
The conventional nasogastric suction catheter of the prior art consists of a long, slender, hollow, flexible tube having a primary suction lumen and a smaller vent lumen. The two lumens are separate and independent from each other. The proximal end of the nasogastric suction catheter is open and is provided with spaced-apart independent couplings, one for the suction lumen and the other for the vent lumen. The coupling for the suction lumen is frequently enlarged and is designed for attachment to the hose of the conventional suction pump. The coupling for the vent lumen may be open to air at atmospheric pressure, or it may be coupled to a reflux valve.
The distal end portion of one representative nasogastric suction catheter is provided with a plurality of openings or suction apertures extending from the suction lumen out through the cylindrical walls of the long, slender, hollow flexible tube to the outside surface of the flexible tube. These suction apertures can vary both in number and size, a typical suction catheter having from six to ten apertures, equally divided on opposite sides of the distal end portion. The length of the distal end portion, with its several suction apertures, may vary from approximately one to three inches, depending in part upon the size and length of the suction catheter and upon the age and size of the patient for which the catheter is to be used.
The distal tip of the conventional nasogastric suction catheter is sealed closed and rounded smooth to aid its intubation through the naris, the esophagus and into the stomach of the patient. The distal end of the vent lumen is open, and the opening may be internal, inside the suction lumen, or both internal and external of the suction lumen. The function of the vent lumen is to allow air to pass from the open proximal end of the suction catheter down through the vent lumen into the stomach of the patient as the contents of the stomach are being withdrawn up through the suction lumen. Additionally, the vent lumen, as well as the suction lumen, can be used as an irrigation lumen to introduce a fluid, such as a saline solution, into the stomach of the patient to aid in flushing residual matter needed to be withdrawn.
The suction apertures of the conventional nasogastric suction catheter usually are punched through the cylindrical wall of the distal end portion and into the suction lumen by a sharp hole-cutting punch. These suction apertures may be oval or circular in shape. The cutting of the suction apertures by the punch leaves sharp edges at the cylindrical surface around the peripheries of the apertures. These sharp peripheral edges are known to cause injury to the patient during both the intubation as well as the suctioning procedures as these apertures rub against the sensitive membranes and linings of the naris, the esophagus, and the inner walls of the stomach. Additionally, as the walls of the stomach begin to collapse as the contents are being withdrawn, the mucosa of the stomach is susceptible to being drawn into the suction apertures, thereby occluding the apertures and causing additional trauma to the patient.
Since the distal end portion of the conventional nasogastric suction catheter is formed at the distal end of the long, slender, hollow flexible tube, the rounded and closed distal tip is of the same material and texture as the long, slender, flexible tube. This distal tip, though rounded smooth, is relatively hard due to the heating and forming required to seal and round the tip during manufacture.
As the distal end portion, with its distal tip, must of necessity be intubated within the stomach, any forceful engagement of the distal tip against the inner walls of the stomach results in trauma to the patient. Because force is required to intubate nasogastric suction catheters, the using physician must exercise due care to properly position the distal end portion within the stomach to minimize trauma.